CIGSSE module pilot processing: from fundamental investigations to advanced performance

A process for high efficiency large area Cu(In,Ga)(Se,S)/sub 2/ thin film (ClGSSe) solar modules is developed applying rapid thermal processing and controlled sodium doping. Continuous optimization targets at sufficient process maturity to successfully transfer into cost effective mass production. The pilot line yields aperture area efficiencies of 11% (average) for 30/spl times/30 cm/sup 2/ modules and a certified champion efficiency of 13.1% for the first 60/spl times/90 cm/sub 2/ demonstrator module unencapsulated. A favourable double band gap grading structure is accomplished by controlled sulfur profiling and by natural gallium accumulation towards the back electrode. The stability of the frameless low cost packaged pilot line modules against humidity is confirmed externally by passing the damp heat test sequence according to IEC 61646. First Cd-free 30/spl times/30 cm/sup 2/ circuits yield up to 11.9% efficiency applying CBD-Zn(S,OH)-buffer layers.